Silencer for firearms discharging gasses at supersonic velocity



Nov. 18, 1969 s. HUBNER 3,478,841

SILENCER FOR FIREARMS DISCHARGING GASSES AT SUPERSONIC VELOCITY Filed July 7, 1967 2 Sheets-Sheet l Fig. 2 20 /N VEN TOR.

Nov. 18, 1969 s. HUBNER 3,

SILENCER FOR FIREARMS DISCHARGING GASSES AT SUPERSONIC VELOCITY Filed July 7, 1967 2 Sheets-Sheet 2 Fig.3

IN VEN TOR:

United States Patent SILENCER FOR FIREARMS DISCHARGING GASSES AT SUPERSONIC VELOCITY Siegfried Hubner, Stuttgart-Heumaden, Germany, assignor to Carl Walther Sportwalfenfabrik, a limited-liability corporation of Germany Filed July 7, 1967, Ser. No. 651,958

Int. Cl. F01n 1/06 US. Cl. 18147 8 Claims ABSTRACT OF THE DISCLOSURE A silencer for gasses discharged at supersonic velocity from the muzzle of a firearm and having a hollow cylindrical casing with end walls. There are aligned openings in the end walls defining a passage therethrough with the inner face of the exit end wall being convex to form a compression wave when discharged gasses impinge on the convex surface.

The present invention relates to a silencer for firearms, more particularly, to such a silencer for gasses discharged at supersonic velocity from the muzzle of a firearm.

Many forms of silencers have been devised for mufliing the report of a discharged firearm. One category of silencers comprises a series of chambers formed by a number of partitions positioned transversely to the path of the bullet. The discharged gasses are conducted through these successive chambers and their energy dissipated before the gasses are emitted to the atmosphere after the bullet. Another class of silencers employs the so-called vortex chamber. All of these known silencers, however, are generally intended for use where the discharge gasses expand at a velocity less than the speed of sound. Silencers used for gasses dischargedat subsonic velocities are not necessarily operative with gasses expanding at supersonic velocities since at supersonic velocities completely different phenomena are known to occur. Accordingly, an insignificant silencing elfect is generally obtained when one tries to employ a silencer intended for subsonic discharge gasses with a firearm from which the gasses are discharged at supersonic velocities.

It is therefore the pincipal object of the present invention to provide a novel and improved silencer for firearms.

It is another object of the present invention to provide a simple, yet effective structure for silencing firearms from which the gasses are discharged at a supersonic velocity.

It is a further object of the present invention to provide a silencer for firearms wherein the gasses discharged at a supersonic velocity will be slowed down to subsonic velocities.

The objects of the present invention are achieved and the disadvantages of the prior art are eliminated by the silencer of the present invention which may comprise a cylindrical hollow body with front and rear end walls. The rear end wall has an entrance opening which is positioned in front of the muzzle opening of the firearm and the front end wall has an exit opening, aligned with the entrance opening, so as to define a path through the cylindrical casing for the bullet. The inner surface of the front end wall surrounding the exit opening defines a convex reflecting surface. As the supersonic gasses enter the cylindrical chamber through the entrance opening, they impinge upon the convex reflecting surface to pro duce a longitudinal compression zone or shock wave. The gasses in the region of this compression zone or 3,478,841 Patented Nov. 18, 1969 wave will be at a higher pressure which in turn will present a corresponding greater opposition to the subsequent approaching discharge gasses. Further, in the re? gion of the compression wave or impulse, the supersonic flow of discharge gasses will be converted to a subsonic flow. The resistance offered by the compression impulse to subsequent discharge gasses is thus seen to increase in proportion to the initial pressure of the discharge gasses. The discharge gasses are thus reversed in direction by the compression impulse by the convex reflector in the casing. The reflected discharge gasses are again reflected when they contact the inner surface of the rear end wall of the silencer. The repeated reflections of the discharge gasses within the silencer will considerably dissipate their energy and decrease their velocity so that when the gasses finally exit from the silencer, their en-. ergy content is quite small.

The reflecting surface for the supersonic discharge velocities is preferably a conical surface surrounding the exit opening and having an angle of at least 30 degrees. Positioned radially outwardly from this supersonic reflecting surface, may be provided a conical reflecting surface for subsonic discharge gasses. Thus the discharge gasses will be reflected within the silencer by both reflecting surfaces.

Other objects and advantages of the present invention will be apparent upon reference to the accompanying description when taken in conjunction with the following drawings wherein:

FIGURE 1 is a longitudinal sectional view of a silencer according to the present invention having 45 degree reflecting surfaces in both ends of the casing;

FIGURE 2 is a view similar to that of FIGURE 1 but showing a modification having a conical reflecting surface surrounding the exit opening;

FIGURE 3 is a view similar to that of FIGURE 1 but showing a further modification wherein a convex reflecting surface surrounds the exit opening in the casing; and

FIGURE 4 is a view similar to that of FIGURE 1 but showing another modification wherein a subsonic diffuser is provided in series behind the conical reflecting surface within the casing of the silencer.

Returning now to the drawing wherein like reference symbols indicate the same parts throughout the various views a specific embodiment and modifications of the present invention will be described in detail.

The silencer of the present invention as illustrated in FIGURE 1 produces a silencing effect by multiple reflections of the expanding discharge gasses within a hollow space 10 formed by a cylindrical casing 11 having a rear end wall 13. The rear end wall is provided with a central entrance opening 18 which is threaded at 15 so that the silencer may be screwed onto the muzzle end of a firearm barrel indicated at 12. The outer peripheral edge of rear end wall 13 is also threaded so that the end wall may be screwed into the cylindrical casing 11.

The other end of casing 11 is closed by a front end wall 14 having an exit opening 19 therein. Exit opening 19 is aligned with entrance opening 18 so as to define a path through the silencer for the bullet. The outer peripheral surface of front end wall 14 is also provided with screw threads so that the front end wall may be threaded into the casing 11. However, the internal threads of casing 11 extend over a distance greater than the length of the front end wall so that the front end wall can be moved to various positions to vary the sapce within the silencer and thus to obtain the maximum silencing effect for different conditions.

The inner face of front end wall 14 is provided with 45 degree reflecting surfaces formed by a V-shaped groove surrounding exit Opening 19. The walls of groove 20 are at a 45 degree angle so that the inner wall immediately adjacent the exit opening forms a convex reflecting surface.

The inner surface of the rear end wall 13 isalso provided with 45 degree reflecting surfaces formed by an annular V-shaped groove 20a surrounding entrance opening 18.

In the modification illustrated in FIGURE 2, the silencer is provided with a front end wall 21 which is threaded into one end of a cylindrical casing 22 so as to define a hollow space 23 in which the silencing effect is created. The inner surface of front end wall 21 is conical as indicated at 24 so as to form an angle of 30 degrees with the central axis of the cone which is substantial-1y the center line of exit opening 19.

The inner face of rear end wall 25 is similarly provided with 45 degree reflecting surfaces formed by a V-shaped groove 20a.

In the silencer according to FIGURE 3, a cylindrical casing has a front end wall 31 threaded therein and a rear end wall 34 similar to the previously described rear end walls. The inner face of front end wall 31 is convex as shown at 33 and opens to the space 32 defined within the silencer.

In the silencer illustrated in FIGURE 4, a cylindrical casing is provided with a rear end wall similar to the previously described rear end walls. The casing 40 defines a space 42 therein in which the silencing effect takes place. The rear end wall is indicated at 41 and has its inner surface formed to define a cone 43 with an opening 44 at the apex thereof. The front end Wall 41 is hollow to define a space 43a which is a diffusion space to receive the subsonic flow of gasses entering through opening 44. The discharge gasses will be repeatedly reflected within the closed space 42 until the gasses are reduced to a subsonic velocity. The subsonic gasses will then pass through the opening 44 to enter the diffusion chamber 43a in which further dissipation of the energy in the discharge gasses will occur.

The internal cross-sectional area of the diffuser increases in the direction of the flow of discharge gasses to decrease further the speed and energy of the gasses.

The rear of the diffusion chamber 43a is closed by a plate 46 having an opening 47 therein through which the gasses are finally discharged to the atmosphere.

It is pointed out that because of the internal configuration of the diffuser space 43a, there will necessarily be large pressure losses at higher Mach numbers which will contribute to greater silencing.

While the silencer in FIGURE 4 illustrates the reflecting surface 43 as being formed separately from the cover 46, it is pointed out that the cover 46 and the wall member 41 may be formed integrally.

During the operation of the silencers described above, it is pointed out that the expanding discharge gasses which leave the muzzle immediately after the projectile or bullet will overtake the projectile in the space enclosed by the cylindrical silencer casing. After repeated reflection of the discharge gasses within the silencer and reducing the supersonic flow of these gasses to a subsonic flow, the gasses will leave the silencer at a relatively slow speed. However, it is pointed out that the successive reflecting movements of the discharged gasses will occur in a relatively short period of time as compared with the time interval between successive shots of the firearm. Time delays incidental to the expulsion of the discharge gasses from the silencer will not slow down in any way the succession of shots of the firearm. There is adequate time available to achieve adequate noise silencing of each shot without any necessity for decreasing the rate of firing.

It is also possible to add a conventional silencer for subsonic discharge gasses at the exit or outlet end of the present silencer. Generally speaking, however, the silencing effect of the present silencer will be sufficient so that an additional subsonic silencer will not be necessary.

Since the silencer of the present invention is particularly constructed for gasses discharged at supersonic velocities, it is necessary that ammunition producing such supersonic discharge velocities be employed. If such ammunition were not used, no compression zone or shock wave would be produced and the present silencer would not beparticularly effective. It is possible, however, to use a Lavall valve which would increase the subsonic velocity of the discharge gasses of ordinary ammunition to super sonic velocity so that the present silencer could be used with ordinary ammunition. As an example of the silencing effect of the present silencer, the silencing effect on a .22 caliber pistol shot amounted to 28 alpha B.

Thus it can be seen that the present invention discloses a silencer for gases discharged at supersonic velocities which employs the shock wave produced by the gasses flowing at such velocities. The reflection of the shock wave from a convex surface will act to dissipate the energy in subsequently flowing discharge gases. The repeated reflections of the discharge gases within the silencer will largely dissipate the energy and sound of the gasses so that the gasses are eventually emitted from the silencer at subsonic velocity. While the present silencer is particularly adapted for firearms, it is not in any way limited to such an application but could be used in any cases where supersonic flow velocities are to be silenced.

It will be understood that the present invention is susceptible to modification in order to adapt it to different usages and conditions.

What is claimed is:

1. A silencer for gasses discharged at supersonic velocity from the muzzle of a firearm and comprising a hollow cylindrical casing having a front end wall and a rear end wall, said rear end wall having an entrance opening therein positionable in front of a muzzle opening through which gasses are discharged at supersonic velocity, said front wall having an exit opening aligned with said entrance opening to define a passage through said casing, said casing being closed except for said entrance and exit openings, said casing and end walls defining a single cylindrical chamber having an unimpeded passage therethrough for the discharged gasses, means within said casing for defining a convex surface surrounding said exit opening so that a longitudinal compression wave formed by discharged gasses impinging at a supersonic velocity on said convex surface acts upon subsequent gasses being discharged from said entrance opening into said casing, and means within said casing for defining a concave conical surface radially outwardly of said convex surface and adjoining thereto for reflecting subsonic gasses impinging thereon.

2. A silencer as claimed in claim 1 with said convex surface and concave surface defining means being integral with said front end wall.

3. A silencer as claimed in claim 1 with said convex surface being conical and being at an angle of at least 30 degrees with the axis of the cone.

4. A silencer as claimed in claim 1 and further comprising diffuser means within said casing behind said convex surface in the direction of expansion of gasses within said casing.

5. A silencer as claimed in claim 4 with said front end wall comprising said diffuser means.

6. A silencer as claimed in claim 1 with the inner face of said rear wall having a portion thereof inclined with respect to a plane perpendicular to the direction of gas expansion in said casing.

7. A silencer as claimed in claim 6 with said inclined portion comprising a conical surface surrounding said entrance opening.

8. A silencer as claimed in claim 1 with there being a V-shaped groove in the inner face of said rear wall surrounding said entrance opening with the sides of said groove being at an angle of 45 degrees with respect to the direction of expansion of gasses within said casing.

FOREIGN PATENTS 1,469,523 1,487,493 References Cited 8153 UNITED STATES PATENTS 5 6,680 2/1912 Kenney s9 14.4 3 38 9/1914 Westfall s9 14.4 3 1 3/1918 Love 89-14.3 12/1937 Green 89-14.3 10

2/1959 Schuessler 8914.3 12/1963 Aulabaugh 89-14.3 181-57; 89-14 France. France. Great Britain. Great Britain. Great Britain. Netherlands.

ROBERT S. WARD, JR., Primary Examiner US. Cl. X.R. 

